1. Field of the Invention
The invention relates to a process for producing a product from an aqueous slurry waste product which is produced in aqueous alkaline sulfur removal process equipment associated with combustion apparatus or other sources of sulfur oxide and to the product of the process.
2. Description of the Prior Art
In U.S. Pat. No. 3,855,391 a process is described for stabilizing aqueous alkaline scrubber waste products. These scrubber waste products normally contain as essential ingredients calcium sulfate dihydrate and calcium sulfite hemihydrate. The patent proposes addition of metal oxide catalysts to the scrubbing equipment to promote the oxidation of the calcium sulfite hemihydrate to the calcium sulfate dihydrate. The resulting sludge, with optimized calcium sulfate, as described in the patent, is separated into two portions. A first portion is calcined at temperatures of 260.degree.-360.degree. F to convert the calcium sulfate dihydrate into calcium sulfate hemihydrate, also known as plaster of Paris. The calcined first portion is recombined with the second portion to convert the calcium sulfate hemihydrate back to calcium sulfate dihydrate and the resulting mixture is thereafter dewatered and sent to a landfill area as a sludge which assertedly stabilizes itself.
One shortcoming of the process is the requirement for oxidizing the sludge in the scrubber. The oxidized sludge creates plugging and clogging difficulties within the scrubber. It would be desirable to create a process for stabilizing aqueous alkaline sludges which does not require the in-scrubber oxidation of the sludge solids, i.e., a process which can utilize the scrubber waste products as received. Such scrubber waste products normally contain at least 30 weight percent calcium sulfite hemihydrate (based on solids).